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Cooking with sewage

Sewage produced in the Thames Valley's now being used to help people cook and heat their homes.

A £2.5m project's started at a sewage works in Didcot, Oxfordshire, to take what's flushed away and turn it into renewable gas that can be fed into the national grid.

It's the first ever project of its kind in the UK, and will help cut greenhouse gas emissions that arise through people cooking and heating their homes using gas sourced from underground.

The project's a joint venture by British Gas, Thames Water and Scotia Gas Networks, and will produce enough renewable gas to supply up to 200 homes.

It's hoped that the project will be the first of many to create renewable heat from waste such as sewage, as the UK aims for its EU goal of supplying 15% of all energy, including heat, from renewables by 2020. It's estimated by National Grid that at least 15% of the domestic gas market could be supplied by renewable gas, known as biomethane, by 2020.

The scheme sees sewage arriving at the Didcot works for treatment, and then sludge - the solid part of the waste - is further treated in a process known as anaerobic digestion in which bacteria break down the biodegradable material and create gas.

The gas is cleaned, with impurities removed, before it is fed into the gas grid, in a process which takes around 20 days from toilet flush to being piped back to people's homes.

Anaerobic digestion is already used to create renewable electricity from sewage - with the gas burned to produce power - but this is the first time the biogas has been pumped directly into the grid for use in homes.

Energy and Climate Change Secretary Chris Huhne said: "It's not every day that a Secretary of State can announce that, for the first time ever in the UK, people can cook and heat their homes with gas generated from sewage.

"This is a historic day for the companies involved, for energy from waste technologies, and for progress to increase the amount of renewable energy in the UK.

"I know there are other similar projects across the country that are close to completion, so this is just the start of a new era of renewable energy."

Under the proposed Renewable Heat Incentive, which was set to be introduced next April but is currently subject to the Government's spending review, subsidies would be paid for renewable gas being put into the grid.

Martin Baggs, Chief Executive of Thames Water, suggested that sewage works across the country were a potential source of renewable gas which could be put to use in their local area.

"We already produce £15 million a year of electricity by burning biogas from the 2.8 billion litres a day of sewage produced by our 14 million customers.

"Feeding this renewable gas directly into the gas grid is the logical next step in our energy from waste business," he said.

Gearoid Lane, managing director of communities and new energy at British Gas, said: "Renewable gas has the potential to make a significant contribution to meeting the UK's energy needs.

"Gas from sewage is just one part of a bigger project, which will see us using brewery and farm waste and farm slurry to generate gas to heat our British Gas homes."

John Morea, chief executive of Scotia Gas Networks, said the process by which gas created from sewage could be supplied back to the homes it came from in the first place was "recycling at its very best".

The launch of the project was celebrated with a breakfast barbecue at Didcot, with bacon sandwiches cooked on a grill powered by the biomethane produced by the scheme.